Spring Integration modeling issue

2
votes

I am a newbie to the Spring Integration framework, so I have questions regarding my current workflow that I need to implement. Not sure how to do proper modeling for that. Here are the steps that need to be done:

  1. Polling filesystem directory for newly arrived XML files (using inbound-channel-adapter). Structure of file is similar to next one:
<user>
    <name>Steve</name>
    <email>[email protected]</email>
    <dateOfBirth>01.01.1990</dateOfBirth>
    <documents>
        <document>
            <fileName>test.pdf</fileName>
        </document>
        <document>
            <fileName>test.mp3</fileName>
        </document>
        <document>
            <fileName>image.png</fileName>
        </document>
        <document>
            <fileName>test2.pdf</fileName>
        </document>
    </documents>
</user>
  1. When XML file is polled, do checking of the documents element whether those (pdf, mp3, images...) exist in the polling directory. If not throw an error and change the extension of the XML file.
  2. If everything ok collects and send each of those documents to the third-party system (custom, independent java library) for optimization.
  3. If optimization was done well, we need to read XML and from data within it create an Object that will be sent to another system for inserting using API with those optimized files.
  4. If that insert goes well, we need to change the XML file by inserting new elements base on the value of the element. Depending on the value XML file will be modified and moved to new folders with all optimized documents contained in that file.

Is this a good use case for Spring Integration? I am not sure how to model this workflow correctly. Can you please give me some tips?

Thanks in advance

1
springspring-integration

1 Answers

1
votes

Your design is correct and it is indeed a fact that Spring Integration with all of its EIP implementations, including MessageChannel abstraction and a set of protocol-specific channel adapters and gateways can help to implement any possible task in the enterprise.

We can't implement everything for you over here. Plus some of the items in your question may deserve their own SO threads. But I'll try to give you some links where to look for info which may help you to proceed with your solution.

First of all it would be great if you have read a EIP Book to understand all the terminology and possible components in the library you are going to use.

Then you go to Spring Integration Reference Manual and scan it for components which can help you to implement particular task in your design.

Let's see what is possible according your description and requests!

  1. You can poll local file system for new files using a FileReadingMessageSource: https://docs.spring.io/spring-integration/docs/current/reference/html/file.html#file-reading

  2. To get a content of that XML file, especially a <documents> tag, you can use an XPathTransformer: https://docs.spring.io/spring-integration/docs/current/reference/html/xml.html#xml-xpath-transformer. Then you split it into a list of file names: https://docs.spring.io/spring-integration/docs/current/reference/html/message-routing.html#splitter. The next one should be a plain transformer to create a java.io.File object or FileInputStream or its byte[]: https://docs.spring.io/spring-integration/docs/current/reference/html/message-transformation.html#messaging-transformation-chapter.

  3. We are not sure how you connect with the third-party system, so, please, be sure that you know what to choose for network interaction. It may be a regular REST service, so you use an HttpRequestExecutingMessageHandler, a TcpOutboundGateway if it is plain TCP/IP connection and so on. You really can find enough of protocol-specific channel adapter implementations in Spring Integration: https://docs.spring.io/spring-integration/docs/current/reference/html/endpoint-summary.html#spring-integration-endpoints.

  4. & 5. Looks more like you need to deal with XML unmarshalling and marshaling in the end: https://docs.spring.io/spring-integration/docs/current/reference/html/xml.html#xml-transformation

For error handling you may consider to wrap some calls into a @MessagingGateway with its errorChannel support: https://docs.spring.io/spring-integration/docs/current/reference/html/messaging-endpoints.html#gateway. Or just add an ExpressionEvaluatingRequestHandlerAdvice to the particular endpoint to simulate a try..catch exactly on that specific logic: https://docs.spring.io/spring-integration/docs/current/reference/html/messaging-endpoints.html#message-handler-advice-chain

See also Spring Integration Samples for some ideas.

You probably going to have more questions, but please, consider to have them as individual most specific SO threads, so we won't pollute this one for non-relevant info.